Calculates dimensions and coordinates for a resized image that fits
within a specified width and height.

Cropping behavior is dependent on the value of $crop:
1. If false (default), images will not be cropped.
2. If an array in the form of array( x_crop_position, y_crop_position ):
- x_crop_position accepts 'left' 'center', or 'right'.
- y_crop_position accepts 'top', 'center', or 'bottom'.
Images will be cropped to the specified dimensions within the defined crop area.
3. If true, images will be cropped to the specified dimensions using center positions.